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Book ChapterDOI

An Overlay Cognitive Radio Model Exploiting the Polarization Diversity and Relay Cooperation

01 Jan 2015-Advances in intelligent systems and computing (Springer India)-pp 125-136

TL;DR: A dual-polarized antenna is incorporated at the secondary transmitter, one of which acts as a relay to the primary user’s signal and cancels out the interference via space–time coding.

AbstractInterference mitigation is one of the significant challenges in overlay cognitive radio (CR). This paper proposes a scheme to avoid the interference in an overlay CR scenario by exploiting the polarization diversity and relay cooperation. In this scheme, a dual-polarized antenna is incorporated at the secondary transmitter, one of which acts as a relay to the primary user’s signal and cancels out the interference via space–time coding. Analytical results about the error performance and the outage probability for the scheme have been calculated. The performance degradation in the absence of perfect CSI has also been shown.

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References
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Journal ArticleDOI
Siavash Alamouti1
TL;DR: This paper presents a simple two-branch transmit diversity scheme that provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas.
Abstract: This paper presents a simple two-branch transmit diversity scheme. Using two transmit antennas and one receive antenna the scheme provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas. It is also shown that the scheme may easily be generalized to two transmit antennas and M receive antennas to provide a diversity order of 2M. The new scheme does not require any bandwidth expansion or any feedback from the receiver to the transmitter and its computation complexity is similar to MRRC.

13,447 citations

Book
01 Jan 2005

9,031 citations

MonographDOI
01 Jan 2005

5,313 citations

Journal ArticleDOI
TL;DR: Signals in the vertical and horizontal polarizations at the base station have been measured by transmitting from a principally vertically polarized mobile by measuring the envelopes and the means differed by 7 dB and 12 dB when the mobile was in urban and suburban areas, respectively.
Abstract: Signals in the vertical and horizontal polarizations at the base station have been measured by transmitting from a principally vertically polarized mobile. There was no direct line-of-sight path between the mobile and base. The envelopes were uncorrelated and the means differed by 7 dB and 12 dB when the mobile was in urban and suburban areas, respectively. The discussion of the results includes theoretical curves showing the relationship between the envelope correction coefficient and the mean levels difference of Rayleigh distributed signals in orthogonal linear polarizations at the base station. The variable parameters are the rotation angle of the base station antenna and the crosspolar discrimination of the incident fields. >

442 citations

Proceedings ArticleDOI
01 Oct 2006
TL;DR: This work summarizes different cognitive radio techniques that underlay, overlay and interweave the transmissions of the cognitive user with those of the licensed users and investigates the inherent tradeoff between the primary detection and the cognitive link capacity.
Abstract: Cognitive radios are promising solutions to the problem of overcrowded and inefficient licensed spectrum. In this work we explore the throughput potential of cognitive communication. We summarize different cognitive radio techniques that underlay, overlay and interweave the transmissions of the cognitive user with those of the licensed users. Recently proposed models for cognitive radios based on the overlay technique are described. For the interweave technique, we present a `two switch' cognitive radio model and develop inner and outer bounds on the secondary radio capacity. Using the two switch model, we investigate the inherent tradeoff between the sensitivity of primary detection and the cognitive link capacity. With numerical results, we compare the throughputs achieved by the secondary user in the different models.

371 citations